Compacting device for dental amalgam

ABSTRACT

A DEVICE FOR COMPACTING AMALGAM USED TO FILL A CAVITY IN A TOOTH. THE COMPACTING IS ACCOMPLISHED BY A RAPIDLY RECIPROCATING SPINDLE OR HAMMER DRIVEN BY A COIL SPRING CONTAINED WITHIN THE DEVICE. THE SPRING CAN BE WOUND BY A FEW TURNS OF THE HANDLE AND PROVIDES MORE THAN ENOUGH ENERGY TO FULLY COMPACT THE AMALGAM REQUIRED FOR A NORMAL FILLING.

Jan; 5, 1971 J. A. GRACEFFO L 3,552,021

COMPACTING DEVICE FOR DENTAL AMALGAM Filed April 9, 1969 I5 7 6 93 86 89 7 8| (he so 28 3 Sheets-Sheet 1 INVENTORS. JOSEPH A GRACEFFO HELIDA R. GRACEFFO Jan. 5, 1971 GRACEFFO ETAL 3,552,)21

COMPACTING DEVICE FOR DENTAL AMALGAM 3 Sheets-Sheet 2 Filed April 9, 1969 AIL ill! Jan. 5, 1971 A'GRACEFFQ ETAL 3,552,021

COMPAC'I'iNG DEVICE FOR DENTAL AMALGAM Filed AprilQ, 1969 3 Sheets-Sheet 5 till 11 III II "I; Ill IE 3,552,021 COMPACTING DEVICE FOR DENTAL AMALGAM Joseph A. Gracelfo and Helida R. Gracefio, both of 60 Cayuga St., Seneca Falls, N.Y. 13148 Filed Apr. 9, 1969, Ser. No. 814,745 Int. Cl. A61c 3/08 U.S. Cl. 32-55 4 Claims ABSTRACT OF THE DISCLOSURE A device for compacting amalgam used to fill a cavity in a tooth. The compacting is accomplished by a rapidly reciprocating spindle or hammer driven by a coil spring contained within the device. The spring can be wound by a few turns of the handle and provides more than enough energy to fully compact the amalgam required for a normal filling.

BACKGROUND OF THE INVENTION This invention relates generally to dental instruments and has particular reference to a novel mechanically operated hand tool for compacting or condensing amalgam, the tool having a self-contained power source.

The most commonly used restorative filling for cavities in teeth is a silver-mercury amalgam which is mixed by the dentist just before use and is in a plastic state when inserted in the cavity. In order for the amalgam material to attain its maximum compressive strength, it must be mechanically compacted or condensed after being placed in the cavity and while still in the plastic state. The dentist may do this by the application of hand pressure to a small packing tool, or he can use a special compacting attachment for his power operated drilling apparatus. The high-speed, power driven compacting attachment does a far better job in almost every instance and, therefore, is the preferred means for performing the operation.

While providing superior results, employment of the power driven compacting attachment has the disadvantage that the dentist must detach the drill contra angle he used to prepare the cavity before he can attach the compacting contra angle to the handpiece of the belt driven power supply apparatus. Likewise, the compacting contra angle must be detached and replaced by the drill contra angle before the latter can be used again. Since the drilling and filling operations generally are alternated throughout the day, the time lost in interchanging the contra angles adds up and becomes a problem to a busy dentist.

In addition to the time lost because of the necessity for interchanging the drilling and compacting contra angles, the dentist may be further delayed by having to change the amalgam engaging tip of the compacting attachment to one of a different size. Normally, this means that he must go over to a cabinet and look in a drawer for the size tip he wants before he can proceed.

SUMMARY OF THE INVENTION The invention to be disclosed herein is a mechanically operated amalgam compacting hand tool that is provided with a self-contained power source in the form of a Windable coil spring. The spring operates through a mechanical linkage to reciprocate a spindle or tip which projects from one end of the tool and is adapted to engage the amalgam to compact same. The linkage con necting this spring with the spindle includes a speed increasing gear train and a governor so that the spindle will be reciprocated at a metered and substantially uniform speed. The drive spring in the tool is wound by rotating a portion of the tool handle, and thereafter the nited States Patent O 3,552,021 Patented Jan. 5, 1971 on-off operation of the tool can be controlled by an externally located trigger element.

The tool of the invention can be constructed as a unitary device or it can be constructed so that it is adapted to incorporate a compacting attachment such as the dentist might have acquired previously for use with his power operated drilling apparatus. In either case, the tool eliminates the serious disadvantage that was noted above because it is a separate and independent device with its own source of power and there is no longer any need to continually change the drilling and compacting contra angles in the power supply apparatus. Another feature of the compacting tool is that storage means are provided in its handle for additional tips of different commonly used sizes. whereby the dentist can quickly and easily change tips without having to move away from the patients chair. In addition to eliminating the disadvantages of the prior art, it is an important object of the invention to provide a compacting device that is dependable, durable and economical to manufacture and use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a compacting tool embodying the invention;

FIG. 2 is an enlarged, fragmentary longitudinal section through the tool of FIG. 1;

FIGS. 3 and 4 are transverse sections through the tool taken substantially on lines 3-3 and 44 of FIG. 2;

FIG. 5 is a diagrammatic illustration of the gear train of the tool;

FIGS. 69 are transverse sections through the tool taken substantially on the lines 66, 7-7, 8-8 and 9-9, respectively, of FIG. 2;

FIGS. 10 and 11 are enlarged top elevations of two of the shaft coupling members;

FIG. 12 is an exploded isometric view of the shaft coupling means; and

FIG. 13 is an enlarged, fragmentary longitudinal section corresponding to a portion of FIG. 2 but illustrating a modified form of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Having particular reference now to FIGS. 1 and 2 of the drawings, the compacting tool is essentially comprised of a handle portion generally indicated at 15 and a contra angle portion generally indicated at 16. An amalgam engaging spindle or tip 17 is mounted for reciprocating movement at the outer end of the contra angle and its offon operation is controlled by a movable actuator or trigger 18, all of which will be described in more detail here inafter. The handle portion 15 comprises a pair of cylinders or barrels 19 and 20, the larger diametered outer barrel 20 being rotatably connected to the barrel 19.

Barrel 20 is formed of two main parts 21, 22, threaded together at 24. The part 21 has a reduced diameter portion 25 which telescopically engages the reduced end 26 of barrel 19, the engagement being with a fit that permits the part 21 to turn freely on the end 26. Part 21 and barrel 19 are held in engagement by a circular plate 27 which bears against an inner annular shoulder 28 on the part 21 and is secured to the closed end 29 of the barrel 19 as by cap screws 30, FIGS. 2 and 4.

An inner cup member 31 is mounted with a press fit in the barrel part 21 and the outer end of this cup is engaged by an inner annular shoulder 32 on the barrel part 22 so that when the two barrel parts are threaded together the cup is rigidly secured in the barrel interior. A coil spring 34 is positioned in the cup 31, and the bent over outer end 35 of this spring, as best seen in FIG. 4, is received in a slot 36 in the cup sidewall to connect the two parts together. The bent inner end 37 of the spring is received in a diametrical slot 38 in a shaft 39, the shaft being journalled, at its outer end, in the end wall of barrel part 22 and, adjacent its inner end, in the end wall 29 of barrel 19. Most of the bottom of cup 31 is removed to permit the shaft to pass therethrough and for an additional purpose to be explained.

It may be seen that when the shaft 39 is held against movement in barrel 19 (by means to be described hereinafter) if the barrel is rotated relative to barrel 19 in the clockwise direction, see FIG. 4, the coil spring 34 will be wound because the cup 31 and outer end 35 of the spring will rotate with barrel 20 while the inner end 37 of the spring is held stationary. To prevent the spring from unwinding and forcing the barrel to rotate in the opposite direction as soon as it is let go, the bottom of the cup is provided with ratchet teeth 40 that are engaged by a pawl 41. The ratchet teeth encircle the portion of the cup bottom that has been removed, being formed in the edge of the opening, while the pawl is pivotally mounted on one of the cap screws 30 and is biased into engagement with the teeth by a spring 42 that extends between another of the cap screws and the pawl as shown in FIG. 4.

Referring again to FIG. 2, the inner end of shaft 39 carries a pinion 44 in mesh with the first gear 45 of a speed increasing gear train 46 of conventional construction. The gears of the gear train assembly are mounted on shafts carried by circular plates 47, 48, the plates being secured together in spaced relation by tie rods 49, FIG. 6. The gear train plates fit in the barrel 19 with the plate 48 abutting an interior annular shoulder 50 in the barrel. Plate 48 is provided with a locating dowel or pin 51 which is received in a complementary bore in the shoulder.

The final or driven gear 52 of the gear train meshes with a pinion 54 mounted on the end of a shaft 55 that is l journalled in the interior transverse wall 56 of an end closure member 57 which is threaded to the barrel 19. The other end of shaft 55 carries a coupling member 58 for connecting the shaft 55 to the shaft 59 of the contra angle 16. Thus, in the form of the invention discloses in FIGS. 1 and 2, the compacting tool is adapted to utilize and incorporate a compacting contra angle attachment such as the dentist might already have in his possession an auxiliary equipment for his power operated drilling apparatus. With this construction, if the dentist already has the compacting attachment, he need only purchase the handle portion 15 to have a complete, self-contained tool. If he does not have a compacting attachment, he can, of course, purchase the complete tool.

It will be understood that shaft 59 is connected in conventional manner through universal coupling means to another shaft, not shown, bearing a cam adjacent the inner end of tip 17 for reciprocating the tip.

In the construction of FIGS. 1 and 2, the end closure 57 terminates in a tubular portion 60 on which the inner I end of the contra angle 16 is telescopically mounted. The latter is releasably held in this position by a spring clip 61 secured by a rivet 62 to the end closure and having a bent over end which enters a shallow annular channel 64 formed on the exterior of the handpiece. As best shown in FIG. 9, the end of the spring clip and the channel in the handpiece are formed with a projection 65 and a notch 66, respectively, which engage to prevent the handpiece from turning relative to the handle portion.

The coupling member 58 is threaded onto the end of shaft 55 and is provided with a cross bore 67 in which a suitable tool can be inserted to tighten the member on the shaft. Thus, in assembling the parts, before the end closure 57 has been threaded into engagement with the barrel 19, a tool can be inserted in the bore 67 through a hole 68 in the end closure sidewall to hold the coupling member while the other end of the shaft, which is more accessible, is turned to thread the member on the shaft. The coupling member 58 is formed with a tenon like projection 69 which is received with a free fit in a slot 70 formed in another coupling member 71. The coupling member 71 and a coacting member 72, FIGS. 2 and 10-12, form an adapter for the contra angle shaft 59 so that it can be coupled to the shaft 55 and driven by the coil spring 34.

Since the end of the shaft 59 will not be threaded if the contra angle 16 has been an attachment for the dentists power operated drilling apparatus, the coupling member 72 is secured thereon by a clamping or chucklike action brought about by its engagement with the member 71. Thus, member 72 is provided with a smooth center bore 74 for receiving the shaft 59, a threaded cylindrical portion 75 and a conical end portion 76 in which a pair of diametrical slots 77 have been cut at right angles to each other. The member 71 is formed with a complementary threaded bore 78 and conical passage 79 so that the member 72 can be engaged therein. However, the taper of the passage 79 is several degrees steeper than that of the conical portion 76 so that as the member 72 advances into member 71 the conical end of the former will be pressed into clamping engagement with the end of the shaft 59 on which the member 72 has been positioned as shown in FIG. 10.

A governor assembly 80 is provided for the shaft 55, comprising a flywheel 81, threadedly secured to the shaft between the pinion 54 and the end wall 56 of the closure member 57, and a pair of movable curved arms or coun terweights 82 are pivotally secured to the flywheel.

Referring to FIG. 7, each arm 82 is pivotally secured at one end to the face of flywheel 81 by a stud 83, the arm being retained on the stud by a bent wire spring 84 having one end secured in a transverse hole in the stud and having its other end bent over the outer edge of the arm 82 for biasing the free end of the arm toward the shaft 55. When the flywheel 81 and shaft 55 rotate at higher speeds the arms 82 are thrown outward against the bias of the springs 84 shifting the mass of the governor 80 outward, thereby slowing the rate of rotation. Similarly, when the rate of rotation is slowed, the arms 82 swing inward, biased by the springs, allowing the shaft and flywheel to rotate faster.

As previously noted, the shaft 39 must be held stationary in the tool in order to wind the coil spring 34. This is accomplished by a brake or friction detent assembly 85 housed in the closure member 57 (FIG. 2). An axially extending plunger shaft 86 has a head 87, of friction material such as leather or plastic, reciprocatively contained in a well bore 88 in the closure member 57 and engageable with the face of flywheel 81 opposite the arms 82. A coil spring 89 around shaft 86 in the bore 88 biases head 87 against the flywheel 81.

Shaft 86 is journalled in the closure member 57, and extends therefrom toward the tip 17 alongside a reduced portion of the closure member which houses the coupling members 58, 71 and 72. The protruding end of shaft 86 is threaded and carries a nut 90.

The actuator 18 has pendant cars 91 (FIGS. 1 and 8) at either side pivotally secured to a portion of the closure member 57 by screws 92 axially aligned below the level of nut 90. The end wall of the actuator between the ears 91 is slotted at 93 so as to extend down on either side of the plunger shaft 88 and to engage the nut 90. When actuator 18 is depressed, therefore, the head 87 is withdrawn from the flywheel 81 and shaft 55 is allowed to rotate, driven by the wound spring 34.

Provision is also made for storage of alternate tips 17 of various sizes in barrel 20 of the device, as shown in FIGS. 2 and 3.

The closed end of portion 22 of the barrel has a plurality of transverse bores 95 of different lengths all opening outward for storage of the spare tips 17' and has an axially projecting threaded boss 96. A circular nut 97 is threadedly secured on the boss 96 and the peripheries of the nut 97 and adjacent portion of barrel portion 22 are grooved at 98 to rotatably contain an endless band or ring 99 which covers the openings of the bores 95 for retaining the tips 17 in the bores. The ring 99 has a single orifice 100 therethrough which can be aligned with a selected one of the bores 95 by rotating band 99 when an alternate tip 17 is desired.

In operation, after the appropriate tip 17 is selected from its storage bore 95 and inserted in the usual manner in the end of the contra angle 16, the dentist-operator rotates the barrel 20, comprising portions 21 and 22, in a clockwise direction in relation to the barrel 19 to wind the spring 34. The device is then ready for use. In a constructed embodiment the barrel 20 may be rotated eight or ten turns which is usually sufficient for the complete compacting of the amalgam in several cavities.

When lever 18 is depressed, the friction head 87 is withdrawn from the flywheel 81 and shaft 39 is allowed to turn, driven by spring 34. Rotation of the shaft 39 is transmitted to the shaft 55 through the gear train 46, and shaft 55 rotates at a regular metered rate of speed controlled by the governor arrangement 80. Rotation of shaft 55 is transmitted to shaft 59 through the coupling 58, 71, 72, and the shaft 59 rotates the cam in the contra angle 16 to rapidly reciprocate the tip 17 which is held against the amalgam to tamp it.

In FIG. 13, a modified form of tamping device 101 is shown fragmentarily as a unitary device not incorporating a compacting attachment adapted to be associated with the dentists power operated drill. No coupling members are necessary and a single shaft 55' extends from pinion 54 into the contra angle portion of the tool.

The closure member 57, which is threadedly secured to the barrel 19' of tool 101, is integral with a housing portion 102 which is similar to the end of the contra angle 16 of the device 15. Shaft 55 carries the flywheel 81' and governor arms 82', like those of the device 15, but extends from where it is journalled in the wall 56' of the closure member 57 through a bushing 103 inside the contra angle portion 102. Shaft 55 is connected by a universal connection to another shaft, not shown, in the contra angle portion, which bears a cam for operating the tip 17, in the same manner as in device 15.

The operation of the device 101 is exactly the same as device 15, being controlled by an actuator 18' which operates a brake detent 85 working on the flywheel 81'. The contra angle portion of the device 101, of course, is not detachable from the end closure member 57 of the device.

We claim:

1. In a hand tool for compacting dental amalgam: a tamping spindle mounted adjacent one end of the tool for reciprocating axial movement relative thereto, a portion of the spindle projecting outwardly from the tool at an angle to the longitudinal axis thereof for engagement with the amalgam; a substantially cylindrical handle portion; a coil spring mounted in said handle portion with its axis in alignment with the longitudinal axis of the handle portion; a part of the handle being rotatable relative to the remainder thereof and operably connected to the spring to wind same; means including a speed increasing gear train and a governor connecting the spring with the spindle so that energy stored in the former can be used to effect the reciprocating movement of the latter; and means, including a trigger element on the exterior of the tool, coacting with said governor for controlling the on-otf operation of the tool.

2. A tool as defined in claim 1 wherein said trigger element is operably connected to a spring biased pressure pad that is normally in frictional engagement with a portion of the governor.

3. A tool as defined in claim 1 wherein said spring and spindle connecting means includes means for changing rotary motion into linear, reciprocating motion, the portion of the tool containing said last-named means and the spindle being connected in a readily releasable manner to the handle portion of the tool.

4. A tool as defined in claim 1 including means in the handle portion for storing additional tamping spindles of different sizes.

References Cited ROBERT PESHOCK, Primary Examiner 

